Synchronous lung cancers defined by deoxyribonucleic acid flow cytometry

When two pulmonary tumors are seen simultaneously in patients with lung cancer, it always raises a question as to whether the lesions are synchronous lung cancers or lung cancer with intrapulmonary metastasis. To settle this issue, we used deoxyribonucleic acid flow cytometry. Deoxyribonucleic acid ploidy patterns of tumors were able to be analyzed in 14 patients with two simultaneous pulmonary tumors resected by operation. These two tumors, with completely different patterns of deoxyribonucleic acid ploidy, were defined as synchronous lung cancers. Tumors were defined as lung cancer with intrapulmonary metastasis when both tumors showed diploidy or when at least one deoxyribonucleic acid index of abnormal clones between two aneuploid tumors was the same or almost identical. Tumors of the five patients with stage I disease were classified as synchronous lung cancers according to the criteria involving deoxyribonucleic acid flow cytometry. Both tumors were adenocarcinomas in four patients and large-cell and squamous cell carcinomas in one. Both tumors in four patients were located in the same lobe but different segments. All but one patient with different histologic types are alive without recurrence from 24 to 100 months after operation. Tumors of the nine patients with stage III disease in whom intrapulmonary metastasis was clinically suspected were classified as lung cancer with intrapulmonary metastasis according to the criteria. These data suggest that deoxyribonucleic acid flow cytometry of tumors may have diagnostic value in determining synchronous lung cancers.